Lactones as new oxygenate fuel additives, fuels based thereon and methods for using same

ABSTRACT

A new oxygenated fuel additive is disclosed, where the additive is a cyclic ester or lactone. A fuel including the new oxygenated fuel additive is disclosed, where the additive is a cyclic ester or lactone. A method is also disclosed for increasing the efficiency of engines and other combustion devices which burn fuels including the the new oxygenated fuel additive is disclosed, where the additive is a cyclic ester or lactone.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to new oxygenate additives for fuels, to fuels including the new fuel additives and to method for making and using same.

More particularly, the present invention relates to new oxygenate additives for fuels, where the additives include cyclic esters having between four and 20 carbon atoms, to fuels including the new fuel additives and to method for making and using same, where the new oxygenate additives improve combustion efficiency and/or reduce emissions.

2. Description of the Related Art

With the phasing out of methyl tertiary butyl ether (MTBE) as an oxygenated fuel additive to enhance combustion efficiency and reduce engine knock in internal combustion engines, many oxygenates such as ethanol have been proposed and tested for this purpose. Each of these alternative oxygenated fuel additives have certain advantages and disadvantages.

With MTBE being taken off the market, ethanol is now the remaining major oxygenate fuel additive. Other tertiary ethers are in use, especially in Europe. Other alcohols and mixtures of alcohols and some ketones are also used for oxygenate fuel additives.

Thus, there is a need in the art for an alternative oxygenate fuel additive with equivalent or superior combustion efficiencies and reduced engine knock or other disadvantages associated with prior art oxygenated fuel additives.

SUMMARY OF THE INVENTION

The present invention provides a fuel additive including one or a plurality of lactones of the general formula (I):

where R¹, R², each R³, each R⁴, R⁵, and R⁶ are the same or different and are selected from the group consisting of a hydrogen atom, an alkyl group having between 1 and about 20 carbon atoms, an aryl group having between about 6 and about 20 carbons atoms, an araalkyl group having between about 7 and about 20 carbons atoms, an alkaaryl group having between about 7 and about 20 carbons atoms, hetero analogs where one or more of the carbon atoms are substituted for oxygen, and n is an integer having a value between 0 and 4 and mixtures or combinations thereof, and where the fuel additive improves combustion efficiency and/or reduces emissions.

The present invention provides a preferred class of new oxygenated fuel additives, where the preferred class includes one or a plurality of four membered lactones of the formula (II):

where R⁷, R⁸, R⁹, and R¹⁰ are the same or different and are selected from the group consisting of a hydrogen atom, an alkyl group having between 1 and about 20 carbon atoms, an aryl group having between about 6 and about 20 carbons atoms, an araalkyl group having between about 7 and about 20 carbons atoms, an alkaaryl group having between about 7 and about 20 carbons atoms, hetero analogs where one or more of the carbon atoms are substituted for oxygen, and mixtures or combinations thereof, and where the fuel additive improves combustion efficiency and/or reduces emissions.

The present invention also provides another preferred class of new oxygenated fuel additives, where the additives including one or a plurality of five-membered lactones of the formula (III):

where R¹¹, R¹², R¹³, R¹⁴, R¹⁵, and R¹⁶ are the same or different and are selected from the group consisting of a hydrogen atom, an alkyl group having between 1 and about 20 carbon atoms, an aryl group having between about 6 and about 20 carbons atoms, an araalkyl group having between about 7 and about 20 carbons atoms, an alkaaryl group having between about 7 and about 20 carbons atoms, hetero analogs where one or more of the carbon atoms are substituted for oxygen, and mixtures or combinations thereof, and where the fuel additive improves combustion efficiency and/or reduces emissions.

The present invention provides another preferred class of new oxygenated fuel additives, where the additives include one or a plurality of six-membered lactones of the formula (IV):

where R¹⁷, R¹⁸, R¹⁹, R²⁰, R²¹, R²², R²³, and R²⁴ are the same or different and are selected from the group consisting of a hydrogen atom, an alkyl group having between 1 and about 20 carbon atoms, an aryl group having between about 6 and about 20 carbons atoms, an araalkyl group having between about 7 and about 20 carbons atoms, an alkaaryl group having between about 7 and about 20 carbons atoms, hetero analogs where one or more of the carbon atoms are substituted for oxygen, and mixtures or combinations thereof, and where the fuel additive improves combustion efficiency and/or reduces emissions.

The present invention provides another preferred class of new oxygenated fuel additives, where the additives include one or a plurality of seven-membered lactones of the formula (V):

where R²⁵, R²⁶, R²⁷, R²⁸, R²⁹, R³⁰, R³¹, R³², R³³, and R³⁴ are the same or different and are selected from the group consisting of a hydrogen atom, an alkyl group having between 1 and about 20 carbon atoms, an aryl group having between about 6 and about 20 carbons atoms, an araalkyl group having between about 7 and about 20 carbons atoms, an alkaaryl group having between about 7 and about 20 carbons atoms, hetero analogs where one or more of the carbon atoms are substituted for oxygen, and mixtures or combinations thereof, and where the fuel additive improves combustion efficiency and/or reduces emissions.

The present invention provides another preferred class of new oxygenated fuel additives, where the additives include one or a plurality of eight-membered lactones of the formula (VI):

where R³⁵, R³⁶, R³⁷, R³⁸, R³⁹, R⁴⁰, R⁴¹, R⁴², R⁴³, R⁴⁴, R⁴⁵, and R⁴⁶ are the same or different and are selected from the group consisting of a hydrogen atom, an alkyl group having between 1 and about 20 carbon atoms, an aryl group having between about 6 and about 20 carbons atoms, an araalkyl group having between about 7 and about 20 carbons atoms, an alkaaryl group having between about 7 and about 20 carbons atoms, hetero analogs where one or more of the carbon atoms are substituted for oxygen, and mixtures or combinations thereof, and where the fuel additive improves combustion efficiency and/or reduces emissions.

The present invention also provides a fuel including a fuel additive having at least one lactone of the general formula (I):

where R¹, R², each R³, each R⁵, and R⁶ are the same or different and are selected from the group consisting of a hydrogen atom, an alkyl group having between 1 and about 20 carbon atoms, an aryl group having between about 6 and about 20 carbons atoms, an araalkyl group having between about 7 and about 20 carbons atoms, an alkaaryl group having between about 7 and about 20 carbons atoms, hetero analogs where one or more of the carbon atoms are substituted for oxygen, and n is an integer having a value between 0 and 4 and mixtures or combinations thereof, and where the fuel additive improves combustion efficiency and/or reduces emissions.

The present invention also provides a fuel additive having one or a plurality of lactones of the general formulas (II-VI) as previously described, where the fuel additive improves combustion efficiency and/or reduces emissions.

The present invention provides a method for reducing emissions and improving combustion efficiencies from the burning of fuels including the steps of:

supplying a fuel including a fuel additive having at least one lactone of the general formula (I):

to an internal combustion engine, a fuel powered generator, or a fossil fuel powered energy conversion unit, and other devices that convert chemical energy in a fuel to mechanical and/or electrical energy.

burning the fuel in the engine, generator or unit to convert stored chemical energy in the fossil fuel to a useable form of energy,

where R¹, R², each R³, each R⁵, and R⁶ are the same or different and are selected from the group consisting of a hydrogen atom, an alkyl group having between 1 and about 20 carbon atoms, an aryl group having between about 6 and about 20 carbons atoms, an araalkyl group having between about 7 and about 20 carbons atoms, an alkaaryl group having between about 7 and about 20 carbons atoms, hetero analogs where one or more of the carbon atoms are substituted for oxygen, and n is an integer having a value between 0 and 4 and mixtures or combinations thereof and where the fuel additive improves combustion efficiency and/or reduces emissions.

The present invention provides a method for reducing emissions and improving combustion from the burning of fossil fuels including the steps of:

supplying a fuel including a fuel additive including at least one lactone of the general formulas (II-VI) as described above to an internal combustion engine, a fossil fuel powered generator, or a fuel powered energy conversion unit, where the fuel additive improves combustion efficiency and/or reduces emissions, and other devices that convert chemical energy in a fuel to mechanical and/or electrical energy, and other energy conversion systems that convert chemical energy stored in a fuel to mechanical and/or electrical energy.

burning the fuel in the engine, generator or unit to convert energy stored in the fuel to a useable form of energy.

DETAILED DESCRIPTION OF THE INVENTION

The inventors have found that lactones, cyclic esters, to have a significantly high blending octane number delineated by the Anti Knock Index (AKI), where the AKI is defined as the arithmetic mean of the Research Octane Number and the Motor Octane Number or AKI=(ROM+MON)/2. The inventors have found that lactones are suitable for blending with gasoline fuels to enhance octane rating and in this manner and perhaps other means to also reduce pollutants when such blended fuels are utilized. The lactones can also be used in other fuels such as diesel, jet fuel, heating oil, etc.

The present invention broadly relates to a fuel additive including a lactone of the general formula (I):

where R¹, R², each R³, each R⁴, R⁵, and R⁶ are the same or different and are selected from the group consisting of a hydrogen atom, an alkyl group having between 1 and about 20 carbon atoms, an aryl group having between about 6 and about 20 carbons atoms, an araalkyl group having between about 7 and about 20 carbons atoms, an alkaaryl group having between about 7 and about 20 carbons atoms, hetero analogs where one or more of the carbon atoms are substituted for oxygen, and n is an integer having a value between 0 and 4 and mixtures or combinations thereof and to fuels including the fuel additives and where the fuel additive improves combustion efficiency and/or reduces emissions.

The present invention also broadly relates to a method for reducing emissions and improving combustion from the burning of fossil fuels including the steps of:

supplying a fuel including a fuel additive having at least one lactone of the general formula (I):

to an internal combustion engine, a fossil fuel powered generator, or a fossil fuel powered energy conversion unit, and other energy conversion systems that convert chemical energy stored in a fuel to mechanical and/or electrical energy, and

burning the fuel in the engine, generator or unit to convert energy stored in the fossil fuel to a useable form of energy,

where R¹, R², each R³, each R⁵, and R⁶ are the same or different and are selected from the group consisting of a hydrogen atom, an alkyl group having between 1 and about 20 carbon atoms, an aryl group having between about 6 and about 20 carbons atoms, an araalkyl group having between about 7 and about 20 carbons atoms, an alkaaryl group having between about 7 and about 20 carbons atoms, hetero analogs where one or more of the carbon atoms are substituted for oxygen, and n is an integer having a value between 0 and 4 and mixtures or combinations thereof and where the fuel additive improves combustion efficiency and/or reduces emissions.

Preferred lactones or cyclic esters include, without limitation, lactones of formulas (II), (III), (IV), (V) and (VI). Particularly preferred lactones include, without limitation, lactones of formula (III) and (IV).

Exemplary examples of lactones suitable for use as a fuel additive of this invention include, without limitation, β-propiolactone or hydracrylic acid β-lactone or 3-hydroxypropionic acid lactone (C₃H₄O₂); γ-crotonolactone or 2-buten-1,4-olide-25H-furanone (C₄H₄O₂); β-butyrolactone or 4-methyl-2-oxetanone or β-methyl-β-propiolactone or 3-hydroxybutyric acid β-lactone (C₄H₆O₂); γ-butyrolactone or 4-hydroxbutyric acid lactone or γ-hydroxybutyric acid lactone (C₄H₆O₂); β-hydroxy-γ-butyrolactone (C₄H₆O₃); α-hydroxy-γ-butyrolactone or 4,5-dihydro-3-hydroxy-23H-furanone (C₄H₆O₃); δ-erythronic acid γ-lactone or δ-erythronolactone or 3-cis-dihydro-3,4-dihydroxy-23H-furanone (C₄H₆O₄); α-methylene-γ-butyrolactone or tulipane or 3-methylenedihydro-23H-furanone (C₅H₆O₂); α-angelicalactone or 5-methyl-23H-furanone or 4-hydroxy-3-pentenoic acid γ-lactone (C₅H₆O₂); α-angelicalactone or 5-methyl-23H-furanone or 4-hydroxy-3-pentenoic acid γ-lactone (C₅H₆O₂); γ-methylene-γ-butyrolactone or 5-methylenedihydro-23H-furanone or α′-angelicalactone (C₅H₆O₂); 5-oxo-2-tetrahydrofurancarboxylic acid or γ-carboxy-γ-butyrolactone or 5-oxotetrahydro-2-furancarboxylic acid (C5H₆O₄); α-methyl-γ-butyrolactone or 4,5-dihydro-3-methyl-23H-furanone (C₅H₈O₂); δ-valerolactone or tetrahydro-2H-2-pyranone (C₅H₈O₂); ±-γ-valerolacton or 4-hydroxypentanoic acid lactone or 4,5-dihydro-5-methyl-23H-furanone or γ-methyl-γ-butyrolactone (C₅H₈O₂); γ-hydroxymethyl-γ-butyrolactone or 5-hydroxymethyl-2-oxotetrahydrofuran or 4,5-dihydro-5-hydroxymethyl-23H-furanone (C₅H₈O₃); dihydro-5-Hydroxymethyl-23H-furanone or 5-hydroxymethyl-2-oxotetrahydrofuran or 4,5-dihydro-5-hydroxymethyl-23H-furanone or γ-hydroxymethyl-γ-butyrolactone (C₅H₈O₃); γ-caprolactone or γ-ethyl-γ-butyrolactone (C₆H₁₀O₂); δ-hexalactone or δ-caprolactone (C₆H₁₀O₂); mevalonolactone or β-hydroxy-β-methyl-δ-valerolactone or 3-hydroxy-3-methyl-δ-valerolactone or mevalolactone or mevalonic acid lactone (C₆H₁₀O₃); dl-α-hydroxy-β,β-dimethyl-γ-butyrolactone or dl-pantolactone or β,β-dimethyl-α-hydroxy-γ-butyrolactone or dihydro-3-hydroxy-4,4-dimethyl-23H-furanone (C₆H₁₀O₃); pantolactone or pantoic acid-γ-lactone or pantolactone or α-hydroxy-β,β-dimethyl-γ-butyrolactone or dihydro-3-hydroxy-4,4-dimethyl-23H-furanone or β,β-dimethyl-α-hydroxy-γ-butyrolactone or δ-pantolactone or δ-pantolactone or α-hydroxy-β,β-dimethyl-γ-butyrolactone (C₆H₁₀O₃); 4-hydroxy-6-methyl-2-pyrone or 3,5-dihydroxysorbic acid δ-lactone (C₆H₆O₃); α-acetyl-α-methyl-γ-butyrolactone (C₇H₁₀O₃); 2,3-o-isopropylidene-δ-erythronolactone or 2,3-o-isopropylidene-δ-erythronolactone (C₇H₁₀O₄); ethyl-5-oxotetrahydro-2-furancarboxylate or δ-ethoxycarbonyl-δ-butyrolactone (C₇H₁₀O₄); γ-ethoxycarbonyl-γ-butyrolactone or ethyl-5-oxotetrahydro-2-furancarboxylate (C₇H₁₀O₄); γ-heptalactone or 4-heptanolide or 4-heptanolide or dihydro-5-propyl-23H-furanone or γ-propyl-γ-butyrolactone (C₇H₁₂O₂); β,β-dimethyl-γ-hydroxy-methyl-γ-butyrolactone (C₇H₁₂O₃); 1,6-dioxaspiro[4.4]nonane-2,7-dione or 4,4-dihydroxypimelic acid dilactone or spirodilactone (C₇H₈O₄); hexahydro-5-hydroxy-4-hydroxymethyl-2H-cyclopenta[β]furan-2-one or Corey lactone (C₈H₁₂O₄); 2-ethoxycarbonyl-4-hydroxy-2-methylbutyric acid γ-lactone (C₈H₁₂O₄); 2,3-o-isopropylidene-δ-ribonic γ-lactone or 2,3-o-isopropylidene-δ-ribonic γ-lactone or 2,3-o-isopropylidene-δ-ribono-1,4-lactone (C₈H₁₂O₅); γ-octalactone, γ-octanoic lactone, (C₈H₁₄O₂); 2,5-dihydroxyphenylacetic acid lactone or homogentisic lactone or 5-hydroxybenzofuran-23H-one (C₈H₆O₃); dehydroacetic acid or 3-acetyl-6-methyl-2H-pyran-2,4-3H-dione or 3-acetyl-4-hydroxy-6-methyl-2-pyrone or 2-acetyl-5-hydroxy-3-oxo-4-hexenoic acid δ-lactone (C₈H₈O₄); 5-hydroxy-2,3-norbomanedicarboxylic acid γ-lactone (C₉H₁₀O₄); α-acryloyloxy-β,β-dimethyl-γ-butyrolactone (C₉H₁₂O₄); α-acryloyloxy-β,β-dimethyl-γ-butyrolactone (C₉H₁₂O₄); 2-ethyl-2-2-hydroxyethyl-glutaric acid γ-lactone (C₉H₁₄O₄); 5,6-o-isopropylidene-1-gulonic acid γ-lactone, (C₉H₁₄O₆); whiskey lactone or 5-butyl-4-methyldihydro-23H-furanone, mixture of cis and trans, (C₉H₁₆O₂); γ-nonanoic lactone (C₉H₁₆O₂); 4-nonanolide or 4,5-dihydro-5-pentyl-23H-furanone or γ-pentyl-g-butyrolactone (C₉H₁₆O₂); δ-nonalactone or 5-hydroxynonanoic acid lactone (C₉H₁₆O₂); γ-phenyl-γ-butyrolactone (C₁₀H₁₀O₂); 6-amyl-α-pyrone or 5-hydroxy-2,4-decadienoic acid γ-lactone (C₁₀H₁₄O₂); 6-amyl-α-pyrone or 5-hydroxy-2,4-decadienoic acid γ-lactone, (C₁₀H₁₄O₂); menthalactone (C₁₀H₁₄O₂); γ-jasmolactone or cis-7-decen-4-olide or cis-γ-3-hexen-1-ylbutyrolactone (C₁₀H₁₆O₂); 4-hydroxy-4-methyl-3-3-oxobutyl-valeric acid γ-lactone (C₁₀H₁₆O₃); δ-decalactone or 5-decanolide or 6-pentyltetrahydro-2H-pyran-2-one or δ-pentyl-δ-valerolactone or 5-hydroxydecanoic acid δ-lactone (C₁₀H₁₈O₂); ε-decalactone or 7-butyl-2-oxepanone (C₁₀H₁₈O₂); γ-decanolactone or 4-hydroxydecanoic acid γ-lactone (C₁₀H₁₈O₂); α-benzylidene-γ-butyrolactone (C₁₁H₁₀O₂); 2-benzyl-3,4-dihydroxycrotonic acid γ-lactone (C₁₁H₁₀O₃); 2-benzyl-3,4-dihydroxycrotonic acid γ-lactone (C₁₁H₁₀O₃); α-2-hydroxybenzylidene-γ-butyrolactone (C₁₁H₁₀O₃); 2,3-cyclohexylidene-δ-ribonic acid γ-lactone, (C₁₁H₁₆O₅); 2-ethoxycarbonyl-2-2-hydroxyethyl-hexanoic acid γ-lactone (C₁₁H₁₈O₄); 2-ethoxycarbonyl-2-2-hydroxyethyl-valeric acid γ Lactone (C₁₁H₁₈O₄); γ-undecalactone (C₁₁H₂₀O₂); δ-undecalactone (C₁₁H₂₀O₂); undecanoic γ-lactone (C₁₁H₂₀O₂); undecanoic δ-lactone (C₁₁H₂₀O₂); Oxacyclododecan-2-one or undecanoic ω-lactone or 1-oxa-2-cyclododecanone and 11-undecanolide (C₁₁H₂₀O₂); 3,4-o-benzylidene-δ-ribonicd-lacton (C₁₂H₁₂O₅); 3,4-o-benzylidene-δ-ribonicd-lactone (C₁₂H₁₂O₅); 2-ethoxycarbonyl 2,2-hydroxyethyl-heptanoic acidy-lactone (C₁₂H₂₀O₄); 2,2-hydroxyethyl-2-isopentylglutaric acid γ-lactone (C₁₂H₂₀O₄); 2-ethoxycarbonyl-2,2-hydroxyethyl-5-methylhexanoic acid γ-lactone (C₁₂H₂₀O₄); δ-dodecalactone or 5-dodecanolide or 5-hydroxydodecanoic acid δ-lactone or 6-heptyltetrahydro-2H-pyran-2-one or δ-heptyl-δ-valerolactone (C₁₂H₂₂O₂); γ-dodecalactone or 4-dodecanolide or dihydro-5-octyl-23H-furanone or γ-octyl-γ-butyrolactone (C₁₂H₂₂O₂); α-acetyl-4-hydroxy-β-Hydroxymethyl-3-methoxycinnamic acid γ-lactone (C₁₃H₁₂O₅); γ-2-naphthyl-g-butyrolactone (C₁₄H₁₂O₂); δ-tetradecalactone (C₁₄H₂₆O₂); ω-pentadecalactone or pentadecanolide or 15-hydroxypentadecanoic acid lactone or 15-pentadecanolide or 1-oxa-2-cyclohexadecanone (C₁₅H₂₈O₂); α,α-diphenyl-γ-butyrolactone or 4-hydroxy-2,2-diphenylbutyric acid γ-lactone (C₁₆H₁₄O₂); ω-6-hexadecenlactone (C₁₆H₂₈O₂); and other lactones or mixtures or combinations thereof, with the understanding that the lactone must be soluble in the fuel it is being added to and improves combustion efficiency and/or reduces emissions.

The particularly preferred lactones are five and six membered ring cyclic esters (compounds of formulas (III) and (IV)) such as gamma-valerolactone (referred to herein as “compound 1”), gamma-caprolactone (referred to herein as “compound 2”), delta-valerolactone (referred to herein as “compound 3”), delta-caprolactone (referred to herein as “compound 4”) and mixtures or combinations thereof.

Suitable fuels for use in this invention include, without limitation, gasoline, diesel, aviation fuel, heating oil, kerosine, etc.

Experimental Section

Testing at Conoco-Phillips Lab afforded an AKI for compound 1 of>112.3 (ROM>120 and MON=104.6) and the AKI for compound 2 is 107.1 (ROM=112.4, MON=101.7). Importantly these were performed as blending octane numbers. Vapor pressures were found to be <0.1 lb for both compound 1 and compound 2, which would theoretically allow a much greater latitude for fuel blending than the more volatile compounds like ethanol, etc. Compound 3 is a larger ring size isomer of compound 1 and compound 4 is similarly a larger ring isomer of 2. Compounds 3 & 4 will likely also be significant octane enhancers. These are presently assigned for similar testing to accurately measure their properties.

Currently some of these compounds are commercially available for many other purposes. They are important flavor and aroma constituents in many natural products. All four of the particularly preferred compounds, compounds 1-4 are available from synthetic sources and biological sources.

The present invention stands in stark contrast to results of Heisler and Eckert disclosed in U.S. Pat. No. 3,015,547. Heisler and Eckert found that when lactones were admixed with high octane gasoline containing tetraethyl lead, “the lactones appear to be ineffective in raising the octane rating of gasolines unless an organo-lead anti-knock agent, normally tetraethyl lead, is a component of the gasoline mixture.” And further, Heisler and Eckert found that these lactones have no effect on a gasoline containing only aliphatic hydrocarbons with no aromatics. The inventors findings are quite opposite.

Five and six membered lactones such as the particularly preferred lactones listed above have relatively high boiling points: compound 1 has a boiling point (bp) 200° C., while the bp of compound 2 is 219° C. Moreover, compounds 1 and 2 have a low vapor pressures and low flash points: compound 1 has a flash point 81° C. and compound 2 has a flash point of 98° C., such compounds normally do not have such high octane numbers. This can be appreciated when compared to the main fuel additives used today; ethanol has a bp of 78° C. and flash point of 16° C. It is thought that the low molecular weight of ethanol and its relatively high oxygen to carbon ratio, makes it ideal as an oxygenate fuel additive. It is believed that the additives of this invention have equivalent or improved additive properties as compared to ethanol due to their relatively low vapor pressure and low flash point.

Lactones of this invention where one of the R¹⁻⁴⁶ groups is a group including a four to six carbon atoms straight chain alkyl group (CH₃(CH₂)_(i)—, where i is 3-18), and all other R groups being hydrogen are ideally suited for diesel additives or for making bio-diesel. These preferred lactones for diesel applications will have high cetane numbers due to the straight chained alkyl group.

In some contrast to the diesel additives of this invention, methyl esters of long chain fatty acids, not cyclic, are used for cetane enhancement in oxygenate fuel additives and as standalone fuel in so-called “biodiesel.” Thus, the diesel lactone additives of this invention represent new and novel cetane enchancers for diesel fuels or for the production of bio-diesel.

The cyclic lactone oxygenated fuel additive of this invention provides an alternative to expensive ethanol as an octane enhancer and oxygenated additive for gasoline and aviation fuels. Some of these lactones have even higher octane numbers than ethanol and much lower Reid vapor pressure values that essentially precludes these compounds from themselves contributing to a vapor that pollutes the atmosphere. The additives of this invention are ideally suited for use in warm climes and seasons where the amount of blended ethanol is limited and for use in high altitude environments where similar constraints are required.

Like ethanol, the lactone fuel additives of this invention can be synthesized form many resources including carbohydrates from biomass. In contrast to MTBE and other ethers used as oxygenated fuel additive, the lactone fuel additives of this invention are naturally occurring compounds, although they can be synthetically prepared. The lactone fuel additives of this invention are also biodegradable because the cyclic ester (lactone) is a naturally occurring and biologically labile functional group.

All references cited herein are incorporated by reference. While this invention has been described fully and completely, it should be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described. 

1. A fuel additive including one or a plurality of lactones of the general formula (I):

where R¹, R², each R³, each R⁴, R⁵, and R⁶ are the same or different and are selected from the group consisting of a hydrogen atom, an alkyl group having between 1 and about 20 carbon atoms, an aryl group having between about 6 and about 20 carbons atoms, an araalkyl group having between about 7 and about 20 carbons atoms, an alkaaryl group having between about 7 and about 20 carbons atoms, hetero analogs where one or more of the carbon atoms are substituted for oxygen, and n is an integer having a value between 0 and 4 and mixtures or combinations thereof.
 2. The additive of claim 1, wherein n is 0 and the additive or additives are four membered lactones of the formula (II):

where R⁷, R⁸, R⁹, and R¹⁰ are the same or different and are selected from the group consisting of a hydrogen atom, an alkyl group having between 1 and about 20 carbon atoms, an aryl group having between about 6 and about 20 carbons atoms, an araalkyl group having between about 7 and about 20 carbons atoms, an alkaaryl group having between about 7 and about 20 carbons atoms, hetero analogs where one or more of the carbon atoms are substituted for oxygen, and mixtures or combinations thereof.
 3. The additive of claim 1, wherein n is 1 and the additive or additives are five membered lactones of the formula (III):

where R¹¹, R¹², R¹³, R¹⁴, R¹⁵, and R¹⁶ are the same or different and are selected from the group consisting of a hydrogen atom, an alkyl group having between 1 and about 20 carbon atoms, an aryl group having between about 6 and about 20 carbons atoms, an araalkyl group having between about 7 and about 20 carbons atoms, an alkaaryl group having between about 7 and about 20 carbons atoms, hetero analogs where one or more of the carbon atoms are substituted for oxygen, and mixtures or combinations thereof.
 4. The additive of claim 1, wherein n is 2 and the additive or additives are six membered lactones of the formula (IV):

where R¹⁷, R¹⁸, R¹⁹, R²⁰, R²¹, R²², R²³, and R²⁴ are the same or different and are selected from the group consisting of a hydrogen atom, an alkyl group having between 1 and about 20 carbon atoms, an aryl group having between about 6 and about 20 carbons atoms, an araalkyl group having between about 7 and about 20 carbons atoms, an alkaaryl group having between about 7 and about 20 carbons atoms, hetero analogs where one or more of the carbon atoms are substituted for oxygen, and mixtures or combinations thereof.
 5. The additive of claim 1, wherein n is 3 and the additive or additives are seven membered lactones of the formula (V):

where R²⁵, R²⁶, R²⁷, R²⁸, R²⁹,R³⁰, R³¹, R³², R³³, and R³⁴ are the same or different and are selected form 5the group consisting of a hydrogen atom, an alkyl group having between 1 and about 20 carbon atoms, an aryl group having between about 6 and about 20 carbons atoms, an araalkyl group having between about 7 and about 20 carbons atoms, an alkaaryl group having between about 7 and about 20 carbons atoms, hetero analogs where one or more of the carbon atoms are substituted for oxygen, and mixtures or combinations thereof.
 6. The additive of claim 1, wherein n is 4 and the additive or additives are eight membered lactones of the formula (VI):

where R³⁵, R³⁶, R³⁷, R³⁸, R³⁹, R⁴⁰, R⁴¹, R⁴², R⁴³, R⁴⁴, R⁴⁵, and R⁴⁶ are the same or different and are selected from the group consisting of a hydrogen atom, an alkyl group having between 1 and about 20 carbon atoms, an aryl group having between about 6 and about 20 carbons atoms, an araalkyl group having between about 7 and about 20 carbons atoms, an alkaaryl group having between about 7 and about 20 carbons atoms, hetero analogs where one or more of the carbon atoms are substituted for oxygen, and mixtures or combinations thereof.
 7. The additive of claim 1, wherein the additive is selected from the group consisting β-propiolactone or hydracrylic acid β-lactone or 3-hydroxypropionic acid lactone (C₃H₄O₂); γ-crotonolactone or 2-buten-1,4-olide-25H-furanone (C₄H₄O₂); β-butyrolactone or 4-methyl-2-oxetanone or β-methyl-β-propiolactone or 3-hydroxybutyric acid β-lactone (C₄H₆O₂); γ-butyrolactone or 4-hydroxbutyric acid lactone or γ-hydroxybutyric acid lactone (C₄H₆O₂); β-hydroxy-γ-butyrolactone (C₄H₆O₃); α-hydroxy-γ-butyrolactone or 4,5-dihydro-3-hydroxy-23H-furanone (C₄H₆O₃); δ-erythronic acid γ-lactone or δ-erythronolactone or 3-cis-dihydro-3,4-dihydroxy-23H-furanone (C₄H₆O₄); α-methylene-γ-butyrolactone or tulipane or 3-methylenedihydro-23H-furanone (C₅H₆O₂); α-angelicalactone or 5-methyl-23H-furanone or 4-hydroxy-3-pentenoic acid γ-lactone (C₅H₆O₂); α-angelicalactone or 5-methyl-23H-furanone or 4-hydroxy-3-pentenoic acid γ-lactone (C₅H₆O₂); γ-methylene-γ-butyrolactone or 5-methylenedihydro-23H-furanone or α′-angelicalactone (C₅H₆O₂); 5-oxo-2-tetrahydrofurancarboxylic acid or γ-carboxy-γ-butyrolactone or 5-oxotetrahydro-2-furancarboxylic acid (C₅H₆O₄); α-methyl-γ-butyrolactone or 4,5-dihydro-3-methyl-23H-furanone (C₅H₈O₂); δ-valerolactone or tetrahydro-2H-2-pyranone (C₅H₈O₂); ±-γ- valerolactone or 4-hydroxypentanoic acid lactone or 4,5-dihydro-5-methyl-23H-furanone or γ-methyl-γ-butyrolactone (C₅H₈O₂); γ-hydroxymethyl-γ-butyrolactone or 5-hydroxymethyl-2-oxotetrahydrofuran or 4,5-dihydro-5-hydroxymethyl-23H-furanone (C₅H₈O₃); dihydro-5-Hydroxymethyl-23H-furanone or 5-hydroxymethyl-2-oxotetrahydrofuran or 4,5-dihydro-5-hydroxymethyl-23H-furanone or γ-hydroxymethyl-γ-butyrolactone (C₅H₈O₃); γ-caprolactone or γ-ethyl-γ-butyrolactone (C₆H₁₀O₂); δ-hexalactone or δ-caprolactone (C₆H₁₀O₂); mevalonolactone or β-hydroxy-β-methyl-δ-valerolactone or 3-hydroxy-3 -methyl-δ-valerolactone or mevalolactone or mevalonic acid lactone (C₆H₁₀O₃); dl-α-hydroxy-β,β-dimethyl-γ-butyrolactone or dl-pantolactone or β,β-dimethyl-α-hydroxy-γ-butyrolactone or dihydro-3-hydroxy-4,4-dimethyl-23H-furanone (C₆H₁₀O₃); pantolactone or pantoic acid-γ-lactone or pantolactone or α-hydroxy-β,β-dimethyl-γ-butyrolactone or dihydro-3-hydroxy-4,4-dimethyl-23H-furanone or β,β-dimethyl-α-hydroxy-γ-butyrolactone or δ-pantolactone or δ-pantolactone or α-hydroxy-β,β-dimethyl-γ-butyrolactone (C₆H₁₀O₃); 4-hydroxy-6-methyl-2-pyrone or 3,5-dihydroxysorbic acid δ-lactone (C₆H₆O₃); α-acetyl-α-methyl-γ-butyrolactone (C₇H₁₀O₃); 2,3-o-isopropylidene-δ-erythronolactone or 2,3-o-isopropylidene-δ-erythronolactone (C₇H₁₀O₄); ethyl-5-oxotetrahydro-2-furancarboxylate or δ-ethoxycarbonyl-δ-butyrolactone (C₇H₁₀O₄); γ-ethoxycarbonyl-γ-butyrolactone or ethyl-5-oxotetrahydro-2-furancarboxylate (C₇H₁₀O₄); γ-heptalactone or 4-heptanolide or 4-heptanolide or dihydro-5-propyl-23H-furanone or γ-propyl-γ-butyrolactone (C₇H₁₂O₂); β,β-dimethyl-γ-hydroxy-methyl-γ-butyrolactone (C₇H₁₂O₃); 1,6-dioxaspiro[4.4nonane-2,7-dione or 4,4-dihydroxypimelic acid dilactone or spirodilactone (C₇H₈O₄); hexahydro-5-hydroxy-4-hydroxymethyl-2H-cyclopenta[β]furan-2-one or Corey lactone (C₈H₁₂O₄); 2-ethoxycarbonyl-4-hydroxy-2-methylbutyric acid γ-lactone (C₈H₁₂O₄); 2,3-o-isopropylidene-δ-ribonic γ-lactone or 2,3-o-isopropylidene-δ-ribonic γ-lactone or 2,3-o-isopropylidene-δ-ribono-1,4-lactone (C₈H₁₂O₅); γ-octalactone, γ-octanoic lactone, (C₈H₁₄O₂); 2,5-dihydroxyphenylacetic acid lactone or homogentisic lactone or 5-hydroxybenzofuran-23H-one (C₈H₆O₃); dehydroacetic acid or 3-acetyl-6-methyl-2H-pyran-2,4-3H-dione or 3-acetyl-4-hydroxy-6-methyl-2-pyrone or 2-acetyl-5-hydroxy-3-oxo-4-hexenoic acid δ-lactone (C₈H₈O₄); 5-hydroxy-2,3-norbomanedicarboxylic acid γ-lactone (C₉H₁₀O₄); α-acryloyloxy-β,β-dimethyl-γ-butyrolactone (C₉H₁₂O₄); α-acryloyloxy-β,β-dimethyl-γ-butyrolactone (C₉H₁₂O₄); 2-ethyl-2-2-hydroxyethyl-glutaric acid γ-lactone (C₉H₁₄O₄); 5,6-o-isopropylidene-1-gulonic acid γ-lactone, (C₉H₁₄O₆); whiskey lactone or 5-butyl-4-methyldihydro-23H-furanone, mixture of cis and trans, (C₉H₁₆O₂); γ-nonanoic lactone (C₉H₁₆O₂); 4-nonanolide or 4,5-dihydro-5-pentyl-23H-furanone or γ-pentyl-g-butyrolactone (C₉H₁₆O₂); δ-nonalactone or 5-hydroxynonanoic acid lactone (C₉H₁₆O₂); γ-phenyl-γ-butyrolactone (C₁₀H₁₀O₂ ); 6-amyl-α-pyrone or 5-hydroxy-2,4-decadienoic acid γ-lactone (C₁₀H₁₄O₂); 6-amyl-α-pyrone or 5-hydroxy-2,4-decadienoic acid γ-lactone, (C₁₀H₁₄O₂); menthalactone (C₁₀H₁₄O₂); γ-jasmolactone or cis-7-decen-4-olide or cis-γ-3-hexen-1-ylbutyrolactone (C₁₀H₁₆O₂); 4-hydroxy-4-methyl-3-3-oxobutyl-valeric acid γ-lactone (C₁₀H₁₆O₃); δ-decalactone or 5-decanolide or 6-pentyltetrahydro-2H-pyran-2-one or δ-pentyl-δ-valerolactone or 5-hydroxydecanoic acid δ-lactone (C₁₀H₁₈O₂); ε-decalactone or 7-butyl-2-oxepanone (C₁₀H₁₈O₂); γ-decanolactone or 4-hydroxydecanoic acid γ-lactone (C₁₀H₁₈O₂); α-benzylidene-γ-butyrolactone (C₁₁H₁₀O₂); 2-benzyl-3,4-dihydroxycrotonic acid γ-lactone (C₁₁H₁₀O₃); 2-benzyl-3,4-dihydroxycrotonic acid γ-lactone (C₁₁H₁₀O₃); α-2-hydroxybenzylidene-γ-butyrolactone (C₁₁H₁₀O₃); 2,3-cyclohexylidene-δ-ribonic acid γ-lactone, (C₁₁H₁₆O₅); 2-ethoxycarbonyl-2-2-hydroxyethyl-hexanoic acid γ-lactone (C₁₁H₁₈O₄); 2-ethoxycarbonyl-2-2-hydroxyethyl-valeric acid γ Lactone (C₁₁H₁₈O₄); γ-undecalactone (C₁₁H₂₀O₂); δ-undecalactone (C₁₁H₂₀O₂); undecanoic γ-lactone (C₁₁H₂₀O₂); undecanoic δ-lactone (C₁₁H₂₀O₂); Oxacyclododecan-2-one or undecanoic ω-lactone or 1-oxa-2-cyclododecanone and 11-undecanolide (C₁₁H₂₀O₂); 3,4-o-benzylidene-δ-ribonicd-lactone (C₁₂H₁₂O₅); 3,4-o-benzylidene-δ-ribonicd-lactone (C₁₂H₁₂O₅); 2-ethoxycarbonyl 2,2-hydroxyethyl-heptanoic acid γ-lactone (C₁₂H₂₀O₄); 2,2-hydroxyethyl-2-isopentylglutaric acid γ-lactone (C₁₂H₂₀O₄); 2-ethoxycarbonyl-2,2-hydroxyethyl-5-methylhexanoic acid γ-lactone (C₁₂H₂₀O₄); δ-dodecalactone or 5-dodecanolide or 5-hydroxydodecanoic acid δ-lactone or 6-heptyltetrahydro-2H-pyran-2-one or δ-heptyl-δ-valerolactone (C₁₂H₂₂O₂); γ-dodecalactone or 4-dodecanolide or dihydro-5-octyl-23H-furanone or γ-octyl-γ-butyrolactone (C₁₂H₂₂O₂); α-acetyl-4-hydroxy-β-Hydroxymethyl-3-methoxycinnamic acid γ-lactone (C₁₃H₁₂O₅); γ-2-naphthyl-g-butyrolactone (C₁₄H₁₂O₂); δ-tetradecalactone (C₁₄H₂₆O₂); ω-pentadecalactone or pentadecanolide or 15-hydroxypentadecanoic acid lactone or 15-pentadecanolide or 1-oxa-2-cyclohexadecanone (C₁₅H₂₈O₂); α,α-diphenyl-γ-butyrolactone or 4-hydroxy-2,2-diphenylbutyric acid γ-lactone (C₁₆H₁₄O₂); ω-6-hexadecenlactone (C₁₆H₂₈O₂); and mixtures or combinations thereof.
 8. The additive of claim 1, wherein the additive is selected from the group consisting of γ-valerolactone, γ-caprolactone, δ-valerolactone and δ-caprolactone and mixtures or combinations thereof.
 9. A fuel composition comprising a fuel and a fuel additive including at least one lactone of the general formula (I):

where R¹, R², each R³, each R⁴, R⁵, and R⁶ are the same or different and are selected from the group consisting of a hydrogen atom, an alkyl group having between 1 and about 20 carbon atoms, an aryl group having between about 6 and about 20 carbons atoms, an araalkyl group having between about 7 and about 20 carbons atoms, an alkaaryl group having between about 7 and about 20 carbons atoms, hetero analogs where one or more of the carbon atoms are substituted for oxygen, and n is an integer having a value between 0 and 4, and mixtures or combinations thereof.
 10. The composition of claim 9, wherein the fuel is selected from the group consisting of gasoline and aviation fuel.
 11. The composition of claim 9, wherein n is 0 and the additive or additives are four membered lactones of the formula (II):

where R⁷, R⁸, R⁹, and R¹⁰ are the same or different and are selected from the group consisting of a hydrogen atom, an alkyl group having between 1 and about 20 carbon atoms, an aryl group having between about 6 and about 20 carbons atoms, an araalkyl group having between about 7 and about 20 carbons atoms, an alkaaryl group having between about 7 and about 20 carbons atoms, hetero analogs where one or more of the carbon atoms are substituted for oxygen, and mixtures or combinations thereof.
 12. The composition of claim 9, wherein n is 1 and the additive or additives are five membered lactones of the formula (III):

where R¹¹, R¹², R¹³, R¹⁴, R¹⁵, and R¹⁶ are the same or different and are selected from the group consisting of a hydrogen atom, an alkyl group having between 1 and about 20 carbon atoms, an aryl group having between about 6 and about 20 carbons atoms, an araalkyl group having between about 7 and about 20 carbons atoms, an alkaaryl group having between about 7 and about 20 carbons atoms, hetero analogs where one or more of the carbon atoms are substituted for oxygen, and mixtures or combinations thereof.
 13. The composition of claim 9, wherein n is 2 and the additive or additives are six membered lactones of the formula (IV):

where R¹⁷, R¹⁸, R¹⁹, R²⁰, R²¹, R²², R²³, and R²⁴ are the same or different and are selected from the group consisting of a hydrogen atom, an alkyl group having between 1 and about 20 carbon atoms, an aryl group having between about 6 and about 20 carbons atoms, an araalkyl group having between about 7 and about 20 carbons atoms, an alkaaryl group having between about 7 and about 20 carbons atoms, hetero analogs where one or more of the carbon atoms are substituted for oxygen, and mixtures or combinations thereof.
 14. The composition of claim 9, wherein n is 3 and the additive or additives are seven membered lactones of the formula (V):

where R²⁵, R²⁶, R²⁷, R²⁸, R²⁹, R³⁰, R³¹, R³², R³³, and R³⁴ are the same or different and are selected from the group consisting of a hydrogen atom, an alkyl group having between 1 and about 20 carbon atoms, an aryl group having between about 6 and about 20 carbons atoms, an araalkyl group having between about 7 and about 20 carbons atoms, an alkaaryl group having between about 7 and about 20 carbons atoms, hetero analogs where one or more of the carbon atoms are substituted for oxygen, and mixtures or combinations thereof.
 15. The composition of claim 9, wherein n is 4 and the additive or additives are eight membered lactones of the formula (VI):

where R³⁵, R³⁶, R³⁷, R³⁸, R³⁹, R⁴⁰, R⁴¹ R⁴², R⁴³, R⁴⁴, R⁴⁵, and R⁴⁶ are the same or different and are selected from the group consisting of a hydrogen atom, an alkyl group having between 1 and about 20 carbon atoms, an aryl group having between about 6 and about 20 carbons atoms, an araalkyl group having between about 7 and about 20 carbons atoms, an alkaaryl group having between about 7 and about 20 carbons atoms, hetero analogs where one or more of the carbon atoms are substituted for oxygen, and mixtures or combinations thereof.
 16. The composition of claim 9, wherein the additive is selected from the group consisting of β-propiolactone or hydracrylic acid β-lactone or 3-hydroxypropionic acid lactone (C₃H₄O₂); γ-crotonolactone or 2-buten-1,4-olide-25H-furanone (C₄H₄O₂); β-butyrolactone or 4-methyl-2-oxetanone or β-methyl-β-propiolactone or 3-hydroxybutyric acid β-lactone (C₄H₆O₂); γ-butyrolactone or 4-hydroxbutyric acid lactone or γ-hydroxybutyric acid lactone (C₄H₆O₂); β-hydroxy-γ-butyrolactone (C₄H₆O₃); α-hydroxy-γ-butyrolactone or 4,5-dihydro-3-hydroxy-23H-furanone (C₄H₆O₃); δ-erythronic acid γ-lactone or δ-erythronolactone or 3-cis-dihydro-3,4-dihydroxy-23H-furanone (C₄H₆O₄); α-methylene-γ-butyrolactone or tulipane or 3-methylenedihydro-23H-furanone (C₅H₆O₂); α-angelicalactone or 5-methyl-23H-furanone or 4-hydroxy-3-pentenoic acid γ-lactone (C₅H₆O₂); α-angelicalactone or 5-methyl-23H-furanone or 4-hydroxy-3-pentenoic acid γ-lactone (C₅H₆O₂); γ-methylene-γ-butyrolactone or 5-methylenedihydro-23H-furanone or α′-angelicalactone (C₅H₆O₂); 5-oxo-2-tetrahydrofurancarboxylic acid or γ-carboxy-γ-butyrolactone or 5-oxotetrahydro-2-furancarboxylic acid (C₅H₆O₄); α-methyl-γ-butyrolactone or 4,5-dihydro-3 -methyl-23H-furanone (C₅H₈O₂); δ-valerolactone or tetrahydro-2H-2-pyranone (C₅H₈O₂); ±-γ-valerolactone or 4-hydroxypentanoic acid lactone or 4,5-dihydro-5-methyl-23H-furanone or γ-methyl-γ-butyrolactone (C₅H₈O₂); γ-hydroxymethyl-γ-butyrolactone or 5-hydroxymethyl-2-oxotetrahydrofuran or 4,5-dihydro-5-hydroxymethyl-23H-furanone (C₅H₈O₃); dihydro-5-Hydroxymethyl-23H-furanone or 5-hydroxymethyl-2-oxotetrahydrofuran or 4,5-dihydro-5-hydroxymethyl-23H-furanone or γ-hydroxymethyl-γ-butyrolactone (C₅H₈O₃); γ-caprolactone or γ-ethyl-γ-butyrolactone (C₆H₁₀O₂); δ-hexalactone or δ-caprolactone (C₆H₁₀O₂); mevalonolactone or β-hydroxy-β-methyl-δ-valerolactone or 3-hydroxy-3-methyl-δ-valerolactone or mevalolactone or mevalonic acid lactone (C₆H₁₀O₃); dl-α-hydroxy-β,β-dimethyl-γ-butyrolactone or dl-pantolactone or β,β-dimethyl-α-hydroxy-γ-butyrolactone or dihydro-3-hydroxy-4,4-dimethyl-23H-furanone (C₆H₁₀O₃); pantolactone or pantoic acid-γ-lactone or pantolactone or α-hydroxy-β,β-dimethyl-γ-butyrolactone or dihydro-3-hydroxy-4,4-dimethyl-23H-furanone or β,β-dimethyl-α-hydroxy-γ-butyrolactone or δ-pantolactone or δ-pantolactone or α-hydroxy-β,β-dimethyl-γ-butyrolactone (C₆H₁₀O₃); 4-hydroxy-6-methyl-2-pyrone or 3,5-dihydroxysorbic acid δ-lactone (C₆H₆O₃); α-acetyl-α-methyl-γ-butyrolactone (C₇H₁₀O₃); 2,3-o-isopropylidene-δ-erythronolactone or 2,3-o-isopropylidene-δ-erythronolactone (C₇H₁₀O₄); ethyl-5-oxotetrahydro-2-furancarboxylate or δ-ethoxycarbonyl-δ-butyrolactone (C₇H₁₀O₄); γ-ethoxycarbonyl-γ-butyrolactone or ethyl-5-oxotetrahydro-2-furancarboxylate (C₇H₁₀O₄); γ-heptalactone or 4-heptanolide or 4-heptanolide or dihydro-5-propyl-23H-furanone or γ-propyl-γ-butyrolactone (C₇H₁₂O₂); β,β-dimethyl-γ-hydroxy-methyl-γ-butyrolactone (C₇H₁₂O₃); 1,6-dioxaspiro[4.4]nonane-2,7-dione or 4,4-dihydroxypimelic acid dilactone or spirodilactone (C₇H₈O₄); hexahydro-5-hydroxy-4-hydroxymethyl-2H-cyclopenta[β]furan-2-one or Corey lactone (C₈H₁₂O₄); 2-ethoxycarbonyl-4-hydroxy-2-methylbutyric acid γ-lactone (C₈H₁₂O₄); 2,3-o-isopropylidene-δ-ribonic γ-lactone or 2,3-o-isopropylidene-δ-ribonic γ-lactone or 2,3-o-isopropylidene-δ-ribono-1,4-lactone (C₈H₁₂O₅); γ-octalactone, γ-octanoic lactone, (C₈H₁₄O₂); 2,5-dihydroxyphenylacetic acid lactone or homogentisic lactone or 5-hydroxybenzofuran-23H-one (C₈H₆O₃); dehydroacetic acid or 3-acetyl-6-methyl-2H-pyran-2,4-3H-dione or 3-acetyl-4-hydroxy-6-methyl-2-pyrone or 2-acetyl-5-hydroxy-3-oxo-4-hexenoic acid δ-lactone (C₈H₈O₄); 5-hydroxy-2,3-norbomanedicarboxylic acid γ-lactone (C₉H₁₀O₄); α-acryloyloxy-β,β-dimethyl-γ-butyrolactone (C₉H₁₂O₄); α-acryloyloxy-β,β-dimethyl-γ-butyrolactone (C₉H₁₂O₄); 2-ethyl-2-2-hydroxyethyl-glutaric acid γ-lactone (C₉H₁₄O₄); 5,6-o-isopropylidene-1-gulonic acid γ-lactone, (C₉H₁₄O₆); whiskey lactone or 5-butyl-4-methyldihydro-23H-furanone, mixture of cis and trans, (C₉H₁₆O₂); γ-nonanoic lactone (C₉H₁₆O₂); 4-nonanolide or 4,5-dihydro-5-pentyl-23H-furanone or γ-pentyl-g-butyrolactone (C₉H₁₆O₂); δ-nonalactone or 5-hydroxynonanoic acid lactone (C₉H₁₆O₂); γ-phenyl-γ-butyrolactone (C₁₀H₁₀O₂); 6-amyl-α-pyrone or 5-hydroxy-2,4-decadienoic acid γ-lactone (C₁₀H₁₄O₂); 6-amyl-α-pyrone or 5-hydroxy-2,4-decadienoic acid γ-lactone, (C₁₀H₁₄O₂); menthalactone (C₁₀H₁₄O₂); γ-jasmolactone or cis-7-decen-4-olide or cis-γ-3-hexen-1-ylbutyrolactone (C₁₀H₁₆O₂); 4-hydroxy-4-methyl-3-3-oxobutyl-valeric acid γ-lactone (C₁₀H₁₆O₃); δ-decalactone or 5-decanolide or 6-pentyltetrahydro-2H-pyran-2-one or δ-pentyl-δ-valerolactone or 5-hydroxydecanoic acid δ-lactone (C₁₀H₁₈O₂); ε-decalactone or 7-butyl-2-oxepanone (C₁₀H₁₈O₂); γ-decanolactone or 4-hydroxydecanoic acid γ-lactone (C₁₀H₁₈O₂); α-benzylidene-γ-butyrolactone (C₁₁H₁₀O₂); 2-benzyl-3,4-dihydroxycrotonic acid γ-lactone (C₁₁H₁₀O₃); 2-benzyl-3,4-dihydroxycrotonic acid γ-lactone (C₁₁H₁₀O₃); α-2-hydroxybenzylidene-γ-butyrolactone (C₁₁H₁₀O₃); 2,3-cyclohexylidene-δ-ribonic acid γ-lactone, (C₁₁H₁₆O₅); 2-ethoxycarbonyl-2-2-hydroxyethyl-hexanoic acid γ-lactone (C₁₁H₁₈O₄); 2-ethoxycarbonyl-2-2-hydroxyethyl-valeric acid γ Lactone (C₁₁H₁₈O₄); γ-undecalactone (C₁₁H₂₀O₂); δ-undecalactone (C₁₁H₂₀O₂); undecanoic γ-lactone (C₁₁H₂₀O₂); undecanoic δ-lactone (C₁₁H₂₀O₂); Oxacyclododecan-2-one or undecanoic ω-lactone or 1-oxa-2-cyclododecanone and 11-undecanolide (C₁₁H₂₀O₂); 3,4-o-benzylidene-δ-ribonicd-lactone (C₁₂H₁₂O₅); 3,4-o-benzylidene-δ-ribonicd-lactone (C₁₂H₁₂O₅); 2-ethoxycarbonyl 2,2-hydroxyethyl-heptanoic acid γ-lactone (C₁₂H₂₀O₄); 2,2-hydroxyethyl-2-isopentylglutaric acid γ-lactone (C₁₂H₂₀O₄); 2-ethoxycarbonyl-2,2-hydroxyethyl-5-methylhexanoic acid γ-lactone (C₁₂H₂₀O₄); δ-dodecalactone or 5-dodecanolide or 5-hydroxydodecanoic acid δ-lactone or 6-heptyltetrahydro-2H-pyran-2-one or δ-heptyl-δ-valerolactone (C₁₂H₂₂O₂); γ-dodecalactone or 4-dodecanolide or dihydro-5-octyl-23H-furanone or γ-octyl-γ-butyrolactone (C₁₂H₂₂O₂); α-acetyl-4-hydroxy-β-Hydroxymethyl-3-methoxycinnamic acid γ-lactone (C₁₃H₁₂O₅); γ-2-naphthyl-g-butyrolactone (C₁₄H₁₂O₂); δ- tetradecalactone (C₁₄H₂₆O₂); ω-pentadecalactone or pentadecanolide or 15-hydroxypentadecanoic acid lactone or 15-pentadecanolide or 1-oxa-2-cyclohexadecanone (C₁₅H₂₈O₂); α,α-diphenyl-γ-butyrolactone or 4-hydroxy-2,2-diphenylbutyric acid γ-lactone (C₁₆H₁₄O₂); ω-6-hexadecenlactone (C₁₆H₂₈O₂); and mixtures or combinations thereof
 17. The composition of claim 9, wherein the additive is selected from the group consisting of γ-valerolactone, γ-caprolactone, δ-valerolactone and δ-caprolactone and mixtures or combinations thereof.
 18. A method for reducing emissions and improving combustion efficiencies from the burning of a fuel including the steps of: supplying a fuel composition comprising a fuel and a fuel additive to an internal combustion engine, a fuel powered generator, or a fuel powered energy conversion unit, and burning the fuel in the engine, generator or unit to convert stored chemical energy in the fuel to a useable form of energy, where the fuel additive comprises at least one lactone of the general formula (I):

where R¹, R², each R³, each R⁴, R⁵, and R⁶ are the same or different and are selected from the group consisting of a hydrogen atom, an alkyl group having between 1 and about 20 carbon atoms, an aryl group having between about 6 and about 20 carbons atoms, an araalkyl group having between about 7 and about 20 carbons atoms, an alkaaryl group having between about 7 and about 20 carbons atoms, hetero analogs where one or more of the carbon atoms are substituted for oxygen, and n is an integer having a value between 0 and 4, mixtures or combinations thereof.
 19. The method of claim 18, wherein the fuel is selected from the group consisting of gasoline and aviation fuel.
 20. The method of claim 14, wherein n is 0 and the additive or additives are four membered lactones of the formula (II):

where R⁷, R⁸, R⁹, and R¹⁰ are the same or different and are selected from the group consisting of a hydrogen atom, an alkyl group having between 1 and about 20 carbon atoms, an aryl group having between about 6 and about 20 carbons atoms, an araalkyl group having between about 7 and about 20 carbons atoms, an alkaaryl group having between about 7 and about 20 carbons atoms, hetero analogs where one or more of the carbon atoms are substituted for oxygen, and mixtures or combinations thereof.
 21. The method of claim 18, wherein n is 1 and the additive or additives are five membered lactones of the formula (III):

where R¹¹, R¹², R¹³, R¹⁴, R¹⁵, and R¹⁶ are the same or different and are selected from the group consisting of a hydrogen atom, an alkyl group having between 1 and about 20 carbon atoms, an aryl group having between about 6 and about 20 carbons atoms, an araalkyl group having between about 7 and about 20 carbons atoms, an alkaaryl group having between about 7 and about 20 carbons atoms, hetero analogs where one or more of the carbon atoms are substituted for oxygen, and mixtures or combinations thereof.
 22. The method of claim 18, wherein n is 2 and the additive or additives are six membered lactones of the formula (IV):

where R¹⁷, R¹⁸, R¹⁹, R²⁰, R²¹, R²², R²³, and R²⁴ are the same or different and are selected from the group consisting of a hydrogen atom, an alkyl group having between 1 and about 20 carbon atoms, an aryl group having between about 6 and about 20 carbons atoms, an araalkyl group having between about 7 and about 20 carbons atoms, an alkaaryl group having between about 7 and about 20 carbons atoms, hetero analogs where one or more of the carbon atoms are substituted for oxygen, and mixtures or combinations thereof.
 23. The method of claim 18, wherein n is 3 and the additive or additives are seven membered lactones of the formula (V):

where R²⁵, R²⁶, R²⁷, R²⁸, R²⁹, R³⁰, R³¹, R³², R³³, and R³⁴ are the same or different and are selected from the group consisting of a hydrogen atom, an alkyl group having between 1 and about 20 carbon atoms, an aryl group having between about 6 and about 20 carbons atoms, an araalkyl group having between about 7 and about 20 carbons atoms, an alkaaryl group having between about 7 and about 20 carbons atoms, hetero analogs where one or more of the carbon atoms are substituted for oxygen, and mixtures or combinations thereof.
 24. The method of claim 18, wherein n is 4 and the additive or additives are eight membered lactones of the formula (VI):

where R³⁵, R³⁶, R³⁷, R³⁸, R³⁹, R⁴⁰, R⁴¹, R⁴², R⁴³, R⁴⁴, R⁴⁵, and R⁴⁶ are the same or different and are selected from the group consisting of a hydrogen atom, an alkyl group having between 1 and about 20 carbon atoms, an aryl group having between about 6 and about 20 carbons atoms, an araalkyl group having between about 7 and about 20 carbons atoms, an alkaaryl group having between about 7 and about 20 carbons atoms, hetero analogs where one or more of the carbon atoms are substituted for oxygen, and mixtures or combinations thereof.
 25. The method of claim 18, wherein the additive is selected from the group consisting β-propiolactone or hydracrylic acid β-lactone or 3-hydroxypropionic acid lactone (C₃H₄O₂); γ-crotonolactone or 2-buten-1,4-olide-25H-furanone (C₄H₄O₂); β-butyrolactone or 4-methyl-2-oxetanone or β-methyl-β-propiolactone or 3-hydroxybutyric acid β-lactone (C₄H₆O₂); γ-butyrolactone or 4-hydroxbutyric acid lactone or γ-hydroxybutyric acid lactone (C₄H₆O₂); β-hydroxy-γ-butyrolactone (C₄H₆O₃); α-hydroxy-γ-butyrolactone or 4,5-dihydro-3-hydroxy-23H-furanone (C₄H₆O₃); δ-erythronic acid γ-lactone or δ-erythronolactone or 3-cis-dihydro-3,4-dihydroxy-23H-furanone (C₄H₆O₄); α-methylene-γ-butyrolactone or tulipane or 3-methylenedihydro-23H-furanone (C₅H₆O₂); α-angelicalactone or 5-methyl-23H-furanone or 4-hydroxy-3-pentenoic acid γ-lactone (C₅H₆O₂); α-angelicalactone or 5-methyl-23H-furanone or 4-hydroxy-3-pentenoic acid γ-lactone (C₅H₆O₂); γ-methylene-γ-butyrolactone or 5-methylenedihydro-23H-furanone or α′-angelicalactone (C₅H₆O₂); 5-oxo-2-tetrahydrofurancarboxylic acid or γ-carboxy-γ-butyrolactone or 5-oxotetrahydro-2-furancarboxylic acid (C₅H₆O₄); α-methyl-γ-butyrolactone or 4,5-dihydro-3-methyl-23H-furanone (C₅H₈O₂); δ-valerolactone or tetrahydro-2H-2-pyranone (C₅H₈O₂); ±-γ-valerolactone or 4-hydroxypentanoic acid lactone or 4,5-dihydro-5-methyl-23H-furanone or γ-methyl-γ-butyrolactone (C₅H₈O₂); γ-hydroxymethyl-γ-butyrolactone or 5-hydroxymethyl-2-oxotetrahydrofuran or 4,5-dihydro-5-hydroxymethyl-23H-furanone (C₅H₈O₃); dihydro-5-Hydroxymethyl-23H-furanone or 5-hydroxymethyl-2-oxotetrahydrofuran or 4,5-dihydro-5-hydroxymethyl-23H-furanone or γ-hydroxymethyl-γ-butyrolactone (C₅H₈O₃); γ-caprolactone or γ-ethyl-γ-butyrolactone (C₆H₁₀O₂); δ-hexalactone or δ-caprolactone (C₆H₁₀O₂); mevalonolactone or β-hydroxy-β-methyl-δ-valerolactone or 3-hydroxy-3-methyl-δ-valerolactone or mevalolactone or mevalonic acid lactone (C₆H₁₀O₃); dl-α-hydroxy-β,β-dimethyl-γ-butyrolactone or dl-pantolactone or β,β-dimethyl-α-hydroxy-γ-butyrolactone or dihydro-3-hydroxy-4,4-dimethyl-23H-furanone (C₆H₁₀O₃); pantolactone or pantoic acid-γ-lactone or pantolactone or α-hydroxy-β,β-dimethyl-γ-butyrolactone or dihydro-3-hydroxy-4,4-dimethyl-23H-furanone or β,β-dimethyl-α-hydroxy-γ-butyrolactone or δ-pantolactone or δ-pantolactone or α-hydroxy-β,β-dimethyl-γ-butyrolactone (C₆H₁₀O₃); 4-hydroxy-6-methyl-2-pyrone or 3,5-dihydroxysorbic acid δ-lactone (C₆H₆O₃); α-acetyl-α-methyl-γ-butyrolactone (C₇H₁₀O₃); 2,3-o-isopropylidene-δ-erythronolactone or 2,3-o-isopropylidene-δ-erythronolactone (C₇H₁₀O₄); ethyl-5-oxotetrahydro-2-furancarboxylate or δ-ethoxycarbonyl-δ-butyrolactone (C₇H₁₀O₄); γ-ethoxycarbonyl-γ-butyrolactone or ethyl-5-oxotetrahydro-2-furancarboxylate (C₇H₁₀O₄); γ-heptalactone or 4-heptanolide or 4-heptanolide or dihydro-5-propyl-23H-furanone or γ-propyl-γ-butyrolactone (C₇H₁₂O₂); β,β-dimethyl-γ-hydroxy-methyl-γ-butyrolactone (C₇H₁₂O₃); 1,6-dioxaspiro[4.4]nonane-2,7-dione or 4,4-dihydroxypimelic acid dilactone or spirodilactone (C₇H₈O₄); hexahydro-5-hydroxy-4-hydroxymethyl-2H-cyclopenta[β]furan-2-one or Corey lactone (C₈H₁₂O₄); 2-ethoxycarbonyl-4-hydroxy-2-methylbutyric acid γ-lactone (C₈H₁₂O₄); 2,3-o-isopropylidene-δ-ribonic γ-lactone or 2,3-o-isopropylidene-δ-ribonic γ-lactone or 2,3-o-isopropylidene-δ-ribono-1,4-lactone (C₈H₁₂O₅); γ-octalactone, γ-octanoic lactone, (C₈H₁₄O₂); 2,5-dihydroxyphenylacetic acid lactone or homogentisic lactone or 5-hydroxybenzofuran-23H-one (C₈H₆O₃); dehydroacetic acid or 3-acetyl-6-methyl-2H-pyran-2,4-3H-dione or 3-acetyl-4-hydroxy-6-methyl-2-pyrone or 2-acetyl-5-hydroxy-3-oxo-4-hexenoic acid δ-lactone (C₈H₈O₄); 5-hydroxy-2,3-norbomanedicarboxylic acid γ-lactone (C₉H₁₀O₄); α-acryloyloxy-β,β-dimethyl-γ-butyrolactone (C₉H₁₂O₄); α-acryloyloxy-β,β-dimethyl-γ-butyrolactone (C₉H₁₂O₄); 2-ethyl-2-2-hydroxyethyl-glutaric acid γ-lactone (C₉H₁₄O₄); 5,6-o-isopropylidene-1-gulonic acid γ-lactone, (C₉H₁₄O₆); whiskey lactone or 5-butyl-4-methyldihydro-23H-furanone, mixture of cis and trans, (C₉H₁₆O₂); γ-nonanoic lactone (C₉H₁₆O₂); 4-nonanolide or 4,5-dihydro-5-pentyl-23H-furanone or γ-pentyl-g-butyrolactone (C₉H,₆O₂); δ-nonalactone or 5-hydroxynonanoic acid lactone (C₉H₁₆O₂); γ-phenyl-γ-butyrolactone (C₁₀H₁₀O₂); 6-amyl-α-pyrone or 5-hydroxy-2,4-decadienoic acid γ-lactone (C₁₀H₁₄O₂); 6-amyl-α-pyrone or 5-hydroxy-2,4-decadienoic acid γ-lactone, (C₁₀H₁₄O₂); menthalactone (C₁₀H₁₄O₂); γ-jasmolactone or cis-7-decen-4-olide or cis-γ-3-hexen-1-ylbutyrolactone (C₁₀H₁₆O₂); 4-hydroxy-4-methyl-3-3-oxobutyl-valeric acid γ-lactone (C₁₀H₁₆O₃); δ-decalactone or 5-decanolide or 6-pentyltetrahydro-2H-pyran-2-one or δ-pentyl-δ-valerolactone or 5-hydroxydecanoic acid 6-lactone (C₁₀H₁₈O₂); ε-decalactone or 7-butyl-2-oxepanone (C₁₀H₁₈O₂); γ-decanolactone or 4-hydroxydecanoic acid γ-lactone (C₁₀H₁₈O₂); α-benzylidene-γ-butyrolactone (C₁₁H₁₀O₂); 2-benzyl-3,4-dihydroxycrotonic acid γ-lactone (C₁₁H₁₀O₃); 2-benzyl-3,4-dihydroxycrotonic acid γ-lactone (C₁₁H₁₀O₃); α-2-hydroxybenzylidene-γ-butyrolactone (C₁₁H₁₀O₃); 2,3-cyclohexylidene-δ-ribonic acid γ-lactone, (C₁₁H₁₆O₅); 2-ethoxycarbonyl-2-2-hydroxyethyl-hexanoic acid γ-lactone (C₁₁H₁₈O₄); 2-ethoxycarbonyl-2-2-hydroxyethyl-valeric acid γ Lactone (C₁₁H₁₈O₄); γ-undecalactone (C₁₁H₂₀O₂); δ-undecalactone (C₁₁H₂₀O₂); undecanoic γ-lactone (C₁₁H₂₀O₂); undecanoic δ-lactone (C₁₁H₂₀O₂); Oxacyclododecan-2-one or undecanoic ω-lactone or 1-oxa-2-cyclododecanone and 11-undecanolide (C₁₁H₂₀O₂); 3,4-o-benzylidene-δ-ribonicd-lactone (C₁₂H₁₂O₅); 3,4-o-benzylidene-δ-ribonicd-lactone (C₁₂H₁₂O₅); 2-ethoxycarbonyl 2,2-hydroxyethyl-heptanoic acid γ-lactone (C₁₂H₂₀O₄); 2,2-hydroxyethyl-2-isopentylglutaric acid γ-lactone (C₁₂H₂₀O₄); 2-ethoxycarbonyl-2,2-hydroxyethyl-5-methylhexanoic acid γ-lactone (C₁₂H₂₀O₄); δ-dodecalactone or 5-dodecanolide or 5-hydroxydodecanoic acid δ-lactone or 6-heptyltetrahydro-2H-pyran-2-one or δ-heptyl-δ-valerolactone (C₁₂H₂₂O₂); γ-dodecalactone or 4-dodecanolide or dihydro-5-octyl-23H- furanone or γ-octyl-γ-butyrolactone (C₁₂H₂₂O₂); α-acetyl-4-hydroxy-β-Hydroxymethyl-3-methoxycinnamic acid γ-lactone (C₁₃H₁₂O₅); γ-2-naphthyl-g-butyrolactone (C₁₄H₁₂O₂); δ-tetradecalactone (C₁₄H₂₆O₂); ω-pentadecalactone or pentadecanolide or 15-hydroxypentadecanoic acid lactone or 15-pentadecanolide or 1-oxa-2-cyclohexadecanone (C₁₅H₂₈O₂); α,α-diphenyl-γ-butyrolactone or 4-hydroxy-2,2-diphenylbutyric acid γ-lactone (C₁₆H₁₄O₂); ω-6-hexadecenlactone (C₁₆H₂₈O₂); and mixtures or combinations thereof.
 26. The method of claim 18, wherein the additive is selected from the group consisting of γ-valerolactone, γ-caprolactone, δ-valerolactone and δ-caprolactone and mixtures or combinations thereof. 